Ticks are ectoparasites that feed on blood and have an impressive ability to consume and process enormous amounts of host blood, allowing extremely long periods of starvation between blood meals. The central role in the parasitic lifestyle of ticks is played by the midgut. This organ efficiently stores and digests ingested blood and serves as the primary interface for the transmission of tick-borne pathogens. In this study, we used a label-free quantitative approach to perform a novel dynamic proteomic analysis of the midgut of Ixodesricinus nymphs, covering their development from unfed to pre-molt stages. We identified 1534 I. ricinus-specific proteins with a relatively low proportion of host proteins. This proteome dataset, which was carefully examined by manual scrutiny, allowed precise annotation of proteins important for blood meal processing and their dynamic changes during nymphal ontogeny. We focused on midgut molecules related to lipid hydrolysis, storage, and transport, opening a yet unexplored avenue for studying lipid metabolism in ticks. Further dynamic profiling of the tick's multi-enzyme digestive network, protease inhibitors, enzymes involved in redox homeostasis and detoxification, antimicrobial peptides, and proteins responsible for midgut colonization by Borrelia spirochetes promises to uncover new targets for targeting tick nymphs, the most critical life stage for transmission the pathogens that cause tick-borne diseases.

Institute of Organic Chemistry and Biochemistry Czech Academy of Sciences Prague Czech Republic

Institute of Parasitology Biology Centre of the Czech Academy of Sciences Ceske Budejovice Czech Republic

Institute of Parasitology Biology Centre of the Czech Academy of Sciences Ceske Budejovice Czech Republic; Bioptic Laboratory Ltd Plzen Czech Republic

Institute of Parasitology Biology Centre of the Czech Academy of Sciences Ceske Budejovice Czech Republic; Faculty of Sciences University of South Bohemia Ceske Budejovice Czech Republic

Vector Biology Section Laboratory of Malaria and Vector Research National Institute of Allergy and Infectious Diseases Bethesda Maryland USA

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The immune factors involved in the rapid clearance of bacteria from the midgut of the tick Ixodes ricinus

An Unusual Two-Domain Thyropin from Tick Saliva: NMR Solution Structure and Highly Selective Inhibition of Cysteine Cathepsins Modulated by Glycosaminoglycans